Variable load brake



June 28, U A VARIABLE LOAD BRAKE Filed oct. 21. 1927 H Y E E M m 4 w A. ai H R A m s M X m m i v Q .g m W m m e 6 A n 2 3 muuu fr ...nl Il!! *x T M x O /M Q, n 3 d O 2. 2c a, 3 8 i 4 VT l Q/l 6 ||1 rr :n 4 O rv j 7 J .m L WHJMNVMMWMJWM r u mw 4 a 4 o, o

Patented `lune 28, i932 UNITED STATES PATENT OFFICE UNCAS A. WHITAKER, F WILMERDING, PENNSYLVANIA, ASSIGNOR '10 THE WEST- ING-HOUSE AIR BRAKE COMPANY, WILIlVIIElRDINCi,v PENNSYLVANIA, A CORPORA- TION 0F PENNSYLVANIA VARIABLE LOAD :BRAKE Application 'med october 21, 1927. serial No. 227,631.

This invention relates to electro-pneumatic brakes, and has for its principal object to provide an electropneumatic brake having means for regulating the braking pressure in proportion to the load on the car.

In the accompanying drawing, the single ligure is a diagrammatic sectional view of a combined electro-pneumatic and variable load brake apparatus embodying my invention.

0 The electro-pneumatic brake portion may comprise an electro-magnet 1v having a core 2, adjacent to the pole of Which is mounted an armature 3. A rod 4 extends through a central bore in the core 2 and one end of the 5 rod engages the armature 3. The opposite end of the rod extends into a chamber 5, provided in the upper end of the core 2, and Within said chamber, the rod is provided With a collar 6, which is engaged by a coil spring 7.

0 A cap member 8, screwed into the upper end of the core 2, provides an abutment forthe spring 7.

Disposed adjacent to and in axial alinement with the armature 3 is a flexible dia- 5 phragm 9, and secured to said diaphragm is a stem which is carried by the armature 3.

A valve 11 seats on a valve seat provided at the lower end of therstem 10 and is provided With a stem 12Which extends Vinto Va central 0 bore of the stem 10. In axialalinement with valve 11 is a valve lhavingl a seat in a partition Wall 14 of casing 15, and is provided.

with a stem 16 which extends through a bore in said wall and engages the valve 11.

5 A source of uid under pressure, such as reservoir 17, Which may be charged through a check valve 18 from the usual brake pipe 19, is connected to a valve chamber 20 which contains the valve 13. The brake cylinder 21 0 is connected through piper22 with the diaphragm chamber 23.

The variable load brakemechanism comprises a plunger 24, one end of'which extends intoa casing 25 which is carried by the spring 5 plank of the car truck, as indicated by the reference numeral 26. The end of the plunger 24 is provided with a head 27 subject on one side to the pressure of a coil spring 28 and on ,the other side to the pressure of a coil 0 spring 29.

A bellV crank lever 30 is pivotally mounted on an arm 31 carried by the casing 15 and one ,arm of the bell crank lever is'pivotally connected/to the upper end of the plunger 24, While pivotally connected to the end of the other arm is a bar 32.

Mounted on theend of the bar 32 is a roller 33 which engages at one side a face 34 in the casing 15 and on the opposite side a fulcrum lever 35. Saidfulcrum lever is pivotally connected at one end to the armature 3. A flexible diaphragm 3G is provided in the casing 15vand secured to said diaphragm is a stem 37, the outer end of Which is pivotally connected to the lever 35.

The chamber 38 at one side of the diaphragm 36`is connected to brake cylinder pipe 22 through a passage 39.

For maintaining the plunger 24 in its position of adjustment according to the load on the car against movement due to vibratory movementof the car body relative to the car truck, a cylinder 40 is provided which contains a double ended piston 41. fulcrumed on a pivot pin 43 is pivotally connected at Vone end to the plunger 24 and is provided at the other end With a rounded end portion 44 which engages inra socket provided in the piston 41.

A reservoir 45 containing a suitable liquid i is connected through a` pipe 46, and a restricted port 47 With the piston chamber 48 at one side of piston 41, and is connected through a pipe 49 and a restricted port 50 with the piston chamber 51 at the opposite side of the piston.

In operation, the spring 7 of the electro-vv pneumatic brake nortion acts through the rod A lever 42 4 against the armature 3 and tends to move the armature avvay from the magnet core 2.

If the magnet 1 be suiciently energized, the, pressure of springr7 Will be overcome by theV force of the magnetic pull of the magnet on the armature 3,50 that said armature will be moved to a" position permitting the valve 13 to be seated'by the `spring 52 and moving the stem 10 Vand diaphragm 9, so that the valve 1i1is unseated. The brake cylinder 21 is then open tothe exhaust through pipe 2,2, chamber 23, andpast the open valve 11 to chamber 53, which is open to the atmosphere through port 54.

If it is desired to eect an application of the brakes, the current flow through the magnet 1 is reduced a certain amount, dependent on the degree of brake cylinder pressure desired. The magnetic pull of the magnet is thus reduced, permitting the spring 7 to eX- ert its pressure through the rod 4 so as to move the armature 3 away from the magnet. By this movement the seat in the stem 1() is iirst brought into engagement with the valve 11 so as to cut oii the exhaust from the brake cylinder, and then further movement causes the valve 13 to be unseated. Fluid under pressure is thensupplied from reservoir 17 and'valve chamber 20 to the brake cylinder.

' Then lthe brake cylinder pressure acting in chamber 23 has been increased to suilicient degree, the diaphragm 9 will be deflected upwardly against the pressure of spring 7 until the valve 11 is permitted to seat, but not sufciently to permit the valve 13 to be unseated.

The above operation, however, is modified by the action of the variable load mechanism in the following manner:

` The plunger 24 being supported by the car truck and the casing 15 being carried by the car body, when the car body is depressed by a load, the movement of the car body relatively to the car truck causes a clockwise movement of the bell crank lever 30 and a corresponding movement of the bar 32 toward the right. W'hen the load on the car is decreased, a counter-clockwise movement of the bell crank lever is caused and a corresponding movement ofthe bar 32 toward the left is effected. The fulcrum roller 33 is thus positioned according to the load ron the car and when the brakes are applied, Huid at brake cylinder pressure is supplied through passage 39 to diaphragm chamber 38 and acts through the diaphragm 36 and the stem 37 on the lever 35. The pressure exerted'on the lever 35 acts on the armature 3 and tends to move same upwardly against the resistance of spring 7, in the same way that brake cylinder pressure in diaphragm chamber 23 acts on diaphragm 9.

For a given reduction in current iow through the magnet 1 in effecting an application of the brakes, the brake cylinder pressure obtained will be less as the load is decreased and the roller 33 is moved toward the left, since as' the roller 33 moves toward the left, the eect ofthe brake cylinder pressure on diaphragm 36 as transmitted to the armature 3 is increased, soY that the armature 3A is moved upwardly to close the supply valve 13 when the brake cylinder pressure has been increased to a degree less thanwould be the case were the variable load mechanism not effective. In a similar manner, as the load on the car is increased, the roller 33 is movedV toward the right andthe effect of the brake cylinder pressure.r on the diaphragm 36y as"v transmitted through the lever 35 is correspondingly reduced, so that a higher brake cylinder pressure is obtained for a given reduction in current flow through the magnet 1.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment. or otherwise than by the terms of the appended claims.

Having no w described my invention, what I claim as new and desire to secure by Letters Paten-t, is

1. The combination Vwith a brake cylinder, of electro-responsive means, a valve operated by said means for su plying luid under pressure to the brake cy inder, and a movable abutment operated by brake cylinder pressure for closing said valve, of a second movable abutment subject to brake cylinder pressure, mechanism operated by said abutment for operating said valve, and means -for controlling the operation of said mechanism according to the load on the car.

2. The combination with a brake cylinder, of an electro-magnet, an armature controlled by said magnet, valve means operated by said armature for supplying fluid under pressure to the brake cylinder, a movable abutment subject to brake cylinder pressure, a fulcrum lever operatively connecting said movable abutment to said armature, and means for adjusting the fulcrum point of said lever according to the load on` the car.

3; The combination with a brake cylinder, of an electro-magnet, an armature controlled by said magnet, valve means operated by said armature for supplying Huid under pressure to. the brake cylinder, a movable abutment subject to brakeA cylinder pressure, a fulcrum lever operatively connecting said movable abutment to said armature, a movable tulcrum member for said lever, and means operated according tothe load on the car for mov ing said member.

4. The combination with a brake cylinder, of electrically controlled means for controlling the supply of fluid under vpressure to the brake cylinder and operated to control the degree of fluid pressure supplied to the brake cylinder according to the degree of pressure impressed thereon,and means for varying the degree of pressure impressed on said electrically controlled means according to the load on the car.

In testimony whereof Ihave hereunto set my hand.

UNCAS A. WHITAKER. 

